This paper is aimed at investigating how the DC corona performance of conductor-to-plane gaps as influenced by a floating grid of metallic parallel wires underneath and parallel to the stressed conductor. The corona current-voltage and corona
current density distribution at ground level are studied experimentally with and without floating grids. The wire-to-wire spacing, number, lateral distribution and
height of grid wires are varied. It is found that the number and distribution of grid wires are the major factors that influence the corona onset voltage

This paper is aimed at investigating how the positive dc corona performance
of conductor-to-plane gaps is influenced by grounded and negatively stressed metallic grids located underneath the coronating conductor. A systematic experimental study is made to investigate the corona current–voltage characteristics and the current density distribution at the ground plane with and without grid. The wire-to-wire spacing, number, lateral distribution and height of grid wires as well as the conductor diameter are varied. The current density distribution at the ground plane is correlated with Warburg law that was proposed for point-plane coronas.

This paper evaluates the influence on the positive DC corona onset voltage in conductor-to-plane gaps of a grid of metallic wires placed underneath and parallel to the stressed conductor. A systematic experimental study investigates the dependency of the onset voltage on the gap geometry and the particulars of grounded and negatively stressed grids. These particulars include the wire-to-wire spacing, number, lateral distribution and height of grid wires. It was found that the number and distribution of grid wires are the major factors that influence the corona onset voltage together with the radius of the stressed conductor. In a theoretical approach, calculated values for the onset voltage of positive corona as influenced by the grid particulars are obtained using a method based on the criterion of onset streamers self-sustained growth. This calls for calculating the electric field in the vicinity of the stressed conductor in the presence of the grid. A comparison is made between the calculated onset voltages and those measured experimentally.

A surface dielectric barrier discharge reactor is used to investigate the destruction of naphthalene, as an example of polycyclic aromatic hydrocarbon compound, in an air stream. The characteristics of the reactor including the current–voltage and the power consumed are examined to evaluate its effectiveness in destroying naphthalene. The effects of different operational parameters including applied voltage, frequency, flow rate and initial concentration of naphthalene on the destruction process are studied. The results indicated that the destruction efficiency decreases with increasing flow rate and increases with an increase in the applied voltage and frequency. Although the destruction efficiency is independent of the initial concentration, the energy efficiency is increased with increasing initial concentration. The study shows that naphthalene is totally destroyed in the reactor, but not completely transformed to CO and CO2. Ozone generated as a byproduct in the reactor did not play a role in the destruction process.

The destruction of naphthalene, as representative polycyclic aromatic hydrocarbons, by surface dielectric barrier discharge is investigated in air as well as dry and humidified nitrogen at ambient temperature. Naphthalene destruction efficiency is evaluated in terms of chemical change vis-a-vis energy utilization. The detected byproducts are qualitatively evaluated in order to understand the role of the active species in the destruction process. The results show that the destruction efficiency and the energy efficiency are higher in the dry nitrogen than in the humidified nitrogen, and these decrease with the increase of the humidity. Measured concentration of ozone as a byproduct qualitatively indicates the roles of oxygen and ozone in the destruction process in air. The analysis of the aerosol particles formed during the destruction process, both in the dry and humidified nitrogen, confirmed the adverse effects of the humidity on the byproducts formation and subsequently on the destruction process.

This study aims to investigate the floristic composition, biological spectrum, chorological affinities, and describes the vegetation inhabiting the main channel and the deltaic part of Wadi Kid as one of the principal coastal wadis in South Sinai. The life-form spectrum in the present study is characteristic of an arid desert region with the dominance of therophytes (30.43% of the total) and chamaephtyes (26.09%), followed by hemicryptophytes (26.09%), phanerophytes (14.49%), geophytes (1.45%) and parasites (1.45%). Phytogeographically, the Saharo-Arabian element forms the major component of the floristic structure. The investigation revealed that Wadi. Kid is potential shelters of 5 vegetation groups. Detrended Correspondence Analysis (DCA) represented the distribution of the recognized groups along the first two axes. Canonical Correspondence Analysis (CCA) indicated that clay, coarse sand, electric conductivity, chlorides, magnesium and calcium were the main soil parameters which determined the distribution of vegetation in the study area.

A new series of coordination polymers of Co(II), Ni(II), Cu(ІІ), Cd(II) and UO2(ІІ), 5-(3-pyridyl)-1,3,4-oxadiazole-
2-thiol (POZT) and benzimidazole (BIMZ) has been prepared and characterized. The compounds have been
characterized based on elemental analysis, FT-IR and electronic spectral studies, thermal analysis and X-ray powder
diffraction. Thermogravimetry (TG), derivative thermogravimetry (DTG) and differential thermal analysis (DTA) have
been used to study the thermal decomposition steps and to calculate the thermodynamic parameters of the nanosized
metal coordination polymers. The kinetic parameters have been calculated making use of the Coats-Redfern
and Horowitz-Metzger equations. The scanning electron microscope SEM photographs and particle size calculations
from the powder XRD data indicate the nano-sized nature of the prepared supramolecular coordination polymers
(average size 17-28 nm). The antimicrobial activity of the synthesized compounds was tested against six fungal and
five bacterial strains. The majority of compounds were effective against the tested microbs. The bacteria and fungi
strains are common contaminants of the environment in Egypt. In this article the studied strains are frequently reported
from contaminated soil, water and food.

A new series of coordination polymers of Co(II), Ni(II), Cu(ІІ), Cd(II) and UO2(ІІ), 5-(3-pyridyl)-1,3,4-oxadiazole-
2-thiol (POZT) and benzimidazole (BIMZ) has been prepared and characterized. The compounds have been
characterized based on elemental analysis, FT-IR and electronic spectral studies, thermal analysis and X-ray powder
diffraction. Thermogravimetry (TG), derivative thermogravimetry (DTG) and differential thermal analysis (DTA) have
been used to study the thermal decomposition steps and to calculate the thermodynamic parameters of the nanosized
metal coordination polymers. The kinetic parameters have been calculated making use of the Coats-Redfern
and Horowitz-Metzger equations. The scanning electron microscope SEM photographs and particle size calculations
from the powder XRD data indicate the nano-sized nature of the prepared supramolecular coordination polymers
(average size 17-28 nm). The antimicrobial activity of the synthesized compounds was tested against six fungal and
five bacterial strains. The majority of compounds were effective against the tested microbs. The bacteria and fungi
strains are common contaminants of the environment in Egypt. In this article the studied strains are frequently reported
from contaminated soil, water and food.

A new series of coordination polymers of Co(II), Ni(II), Cu(ІІ), Cd(II) and UO2(ІІ), 5-(3-pyridyl)-1,3,4-oxadiazole-
2-thiol (POZT) and benzimidazole (BIMZ) has been prepared and characterized. The compounds have been
characterized based on elemental analysis, FT-IR and electronic spectral studies, thermal analysis and X-ray powder
diffraction. Thermogravimetry (TG), derivative thermogravimetry (DTG) and differential thermal analysis (DTA) have
been used to study the thermal decomposition steps and to calculate the thermodynamic parameters of the nanosized
metal coordination polymers. The kinetic parameters have been calculated making use of the Coats-Redfern
and Horowitz-Metzger equations. The scanning electron microscope SEM photographs and particle size calculations
from the powder XRD data indicate the nano-sized nature of the prepared supramolecular coordination polymers
(average size 17-28 nm). The antimicrobial activity of the synthesized compounds was tested against six fungal and
five bacterial strains. The majority of compounds were effective against the tested microbs. The bacteria and fungi
strains are common contaminants of the environment in Egypt. In this article the studied strains are frequently reported
from contaminated soil, water and food.

The mechanism of coupled migration and shear is studied in a range of [0001] tilt boundaries in hexagonal close-packed metal using
atomic-scale computer simulation. Symmetrical tilt boundaries spanning the low- and high-angle regimes and comprising regular arrays
of grain boundary dislocations are simulated. For each misorientation, h, the perfect boundary (pristine) is investigated as well as one
containing a disconnection. Both types of structures are subjected to incremental applied strains to determine the stress that produces
coupled migration and shear. The stress for motion in the pristine case, entailing nucleation, is higher than the Peierls stress for motion
when disconnections are present. We conclude that the applied stresses in our simulations exert a Peach–Koehler force on pre-existing
disconnections, thereby providing a feasible mechanism with a well-defined driving force that produces coupled migration and shear.
This mechanism is feasible for the lower-angle boundaries studied, and facile for the high-angle cases.
 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.